Method of using ventricular restoration patch

ABSTRACT

A ventricular patch to restore the ventricular architecture of the heart includes a sheet of biocompatible material having a generally oval configuration, and a continuous ring fixed to the sheet. The ring has a generally oval configuration similar to the generally oval configuration of the sheet of biocompatible material. The ring defines a central generally oval region of the patch inside the ring and a circumferential region of the patch outside of the ring. The central generally oval region has a major axis and a minor axis. The ratio of the major axis to the minor axis is about 4:1.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates generally to surgical methods andapparatus for addressing ischemic cardiomyopathy, and more specificallyto methods and apparatus for restoring the architecture and normalfunction of a mammalian heart.

[0003] 2. Discussion of the Prior Art

[0004] The function of a heart in an animal is primarily to deliverlife-supporting oxygenated blood to tissue throughout the body. Thisfunction is accomplished in four stages, each relating to a particularchamber of the heart. Initially deoxygenated blood is received in theright auricle of the heart. This deoxygenated blood is pumped by theright ventricle of the heart to the lungs where the blood is oxygenated.The oxygenated blood is initially received in the left auricle of theheart and ultimately pumped by the left ventricle of the heartthroughout the body. It can be seen that the left ventricular chamber ofthe heart is of particular importance in this process as it is reliedupon to pump the oxygenated blood initially through a mitral valve intoand ultimately throughout the entire vascular system.

[0005] A certain percentage of the blood in the left ventricle is pumpedduring each stroke of the heart. This pumped percentage, commonlyreferred to as the ejection fraction, is normally about sixty percent.It can be seen that in a heart having a left ventricular volume such asseventy milliliters, an ejection fraction of sixty percent would deliverapproximately 42 milliliters of blood into the aorta. A heart withreduced left ventricular volume might have an ejection fraction of only40% and provide a stroke volume of only 28 millimeters.

[0006] Realizing that the heart is part of the body tissue, and theheart muscle also requires oxygenated blood, it can be appreciated thatthe normal function of the heart is greatly upset by clotting or closureof the coronary arteries. When the coronary arteries are blocked, anassociate portion of the heart muscle becomes oxygen-starved and beginsto die. This is clinically referred to as a heart attack. Ischemiccardiomyopathy typically occurs as the rest of the heart dilates in anattempt to maintain the heart's output to the body.

[0007] As the ischemic area loses its contraction, the area ofdilatation is restricted to the remaining muscle. The three regions oftypical infarction include, 1) the anterior wall septum andanterolateral wall which are supplied by the anterior descendingcoronary artery; 2) the septum and inferior wall supplied by the leftanterior artery and the right coronary artery which narrows due to theheart's elliptical shape; and 3) the lateral wall supplied by thecircumflex artery which perfuses the lateral wall including thepapillary muscle attachments to the ventricular wall.

[0008] As the ischemic cardiomyopathy progresses, the various structuresof the heart are progressively involved including the septum, the apexand the anterolateral wall of the left ventricle. Within a particularwall, the blood starvation begins at the inside of the wall andprogresses to the outside of the wall. It can be seen that addressingischemic cardiomyopathy shortly after the heart attack can limit thedetrimental effects to certain elements of the heart structure, as wellas the inner most thicknesses of the walls defining those structures.

[0009] As a heart muscle is denied blood nourishment support, itsability to participate, let alone aid, in the cardiac pumping function,is greatly diminished and typically nil. Such muscle is commonlyreferred to as akinetic, meaning it does not move. In some cases thewall will form elastic scar tissue which tends to balloon in response tothe pumping action. This muscle tissue is not only akinetic, in that itdoes not contribute to the pumping function, but it is in factdyskinetic, in that it detracts from the pumping function.

[0010] The akinetic tissue will, in addition to not contracting, causecardiac enlargement due to dilatation or loss of its contractilecapacity. The dilatation will widen, and thereby change the fiberorientation of the remaining muscle in the left ventricle. This willmake the ventricle spherical, and change it from the normal ellipticalform which optimizes contraction.

[0011] The shape of the ventricle is normally elliptical or conical withan apex that allows a 60 degree fiber orientation of the muscle. Thisorientation ensures efficient development of intramuscular torsion tofacilitate the pumping of blood. Compression of the left ventricularcavity occurs by torsional defamation which thickens the leftventricular wall. This increases progressively from the mid-ventricularwall to the apex. As a result, maintenance of the apical anchor is acentral theme of cardiac contraction.

[0012] Perhaps the most notable symptom of ischemic cardiomyopathy isthe reduction in the ejection fraction which may diminish, for example,from a normal sixty percent to only twenty percent. This resultsclinically in fatigue, and inability to do stressful activities, thatrequire an increase in output of blood from the heart. The normalresponse of the heart to a reduction in ejection fraction is to increasethe size of the ventricle so that the reduced percentage continues todeliver the same amount of oxygenated blood to the body. By way ofexample, the volume of the left ventricle may double in size.Furthermore, a dilated heart will tend to change its architecture fromthe normal conical or apical shape, to a generally spherical shape. Theoutput of blood at rest is kept normal, but the capacity to increaseoutput of blood during stress (i.e., exercise, walking) is reduced. Ofcourse, this change in architecture has a dramatic effect on wallthickness, radius, and stress on the heart wall. In particular, it willbe noted that absent the normal conical shape, the twisting motion atthe apex, which can account for as much as one half of the pumpingaction, is lost. As a consequence, the more spherical architecture mustrely almost totally on the lateral squeezing action to pump blood. Thislateral squeezing action is inefficient and very different from the moreefficient twisting action of the heart. The change in architecture ofthe heart will also typically change the structure and ability of themitral valve to perform its function in the pumping process. Valvularinsufficiency can also occur due to dilatation.

[0013] A major determinant of both cardiac oxygen requirement andefficiency is based upon a formula where stress or pressure ismultiplied by the radius and divided by twice the thickness of thecardiac wall. Increasing stress reduces contractility or rejectingcapacity, and raises energy requirements in the remaining contractingmuscle. As the shape changes from elliptical to spherical, wall stressincreases thereby demanding higher energy from the remaining cardiacmuscle. This dilation, which occurs anteriorly, effects the septum, apexand anterolateral wall. Thus, the normally oval apex becomes morespherical due to 1) a loss of infarcted muscle, and 2) dilation of theremaining contracting muscle.

[0014] Although the dilated heart may be capable of sustaining life, itis significantly stressed and rapidly approaches a stage where it can nolonger pump blood effectively. In this stage, commonly referred to ascongestive heart failure, the heart becomes distended and is generallyincapable of pumping blood returning from the lungs. This furtherresults in lung congestion and fatigue. Congestive heart failure is amajor cause of death and disability in the United States whereapproximately 400,000 cases occur annually.

[0015] Following coronary occlusion, successful acute reperfusion bythrombolysis, (clot dissolution) percutaneous angioplasty, or urgentsurgery can decrease early mortality by reducing arrhythmias andcardiogenic shock. It is also known that addressing ischemiccardiomyopathy in the acute phase, for example with reperfusion, maysalvage the epicardial surface. Although the myocardium may be renderedakinetic, at least it is not dyskinetic. Post-infarction surgicalrevascularization can be directed at remote viable muscle to reduceischemia. However, it does not address the anatomical consequences ofthe akinetic region of the heart that is scarred. Despite thesetechniques for monitoring ischemia, cardiac dilation and subsequentheart failure continue to occur in approximately fifty percent ofpost-infarction patients discharged from the hospital.

[0016] The distribution of heart failure is more common with occlusionof the left anterior descending coronary artery (LAD) due to itsperfusion of the apex. But, this can also occur with inferiorinfarction, especially if there is inadequate blood supply to the apexdue to 1) prior damage to the left anterior descending artery, or 2)inadequate blood supply due to stenosis or poor function. In general,the distribution of ischemia is 45% anterior, 40% inferior, and 15%circumflex. However, the incidence of congestive heart failure is morecommon in the anterior infarction.

[0017] Various surgical approaches have been taken primarily to reducethe ventricular volume. This is also intended to increase the ejectionfraction of the heart. In accordance with one procedure, viable muscleis removed from the heart in an attempt to merely reduce its volume.This procedure, which is typically accomplished on a beating heart, hasbeen used for hearts that have not experienced coronary disease, butnevertheless, have dilated due to leaking heart valves. Other attemptshave been made to remove the scarred portion of the heart and to closethe resulting incision. This has also had the effect of reducing theventricular volume.

[0018] In a further procedure, a round, circular patch has been proposedfor placement typically in the lateral ventricular wall. Unfortunately,providing the patch with a circular shape has allowed the dilated heartto remain somewhat enlarged with a thin and over-stressed wall section.The exact placement of the patch has been visually determined using onlya visual indication where the typically white scar tissue meets thetypically red normal tissue. Location of the patch has been facilitatedin a further procedure where a continuous suture has been placed aroundthe ventricular wall to define a neck for receiving the patch. The neckhas been formed in the white scar tissue rather than the soft viablemuscle. This procedure has relied on cardioplegia methods to stop thebeating of the heart and to aid in suture placement.

[0019] In the past, the patch has been provided with a fixed orsemi-rigid wall which has prevented the muscle from becoming reduced toan apical anchor which facilitates the twisting motion. The patches havehad a fixed planar configuration which have prevented the lateral musclefrom coapting to form an apex.

[0020] These surgical procedures have been met with some success as theejection fraction has been increased, for example, from twenty-fourpercent to forty-two percent. However, despite this level of success,little attention has been paid to myocardial protection, the potentialfor monitoring the writhing action associated with apical structure, orthe preferred structure for the patch. Failure to protect the heartduring restoration of the segment has increased hospital mortality,morbidity, and irreversibly damaged some normal muscle needed tomaintain the heart's output.

SUMMARY OF THE INVENTION

[0021] An aspect of the invention involves a ventricular patch torestore the ventricular architecture of the heart. The ventricular patchincludes a sheet of biocompatible material having a generally ovalconfiguration, and a continuous ring fixed to the sheet. The ring has agenerally oval configuration similar to the generally oval configurationof the sheet of biocompatible material. The ring defines a centralgenerally oval region of the patch inside the ring and a circumferentialregion of the patch outside of the ring. The central generally ovalregion has a major axis and a minor axis. The ratio of the major axis tothe minor axis is about 4:1. In a preferred implementation, the centralgenerally oval region has a major axis of about 4 cm and a minor axis ofabout 1 cm.

[0022] Another aspect of the invention involves a ventricular patch torestore the ventricular architecture of the heart. The ventricular patchincludes a sheet of biocompatible material having a generally ovalconfiguration and a continuous ring fixed to the sheet. The continuousring includes a generally oval configuration similar to the generallyoval configuration of the sheet of biocompatible material, and defines acentral generally oval region of the patch inside the ring and acircumferential region of the patch outside of the ring. The centralgenerally oval region has a major axis and a minor axis. The ratio ofthe major axis to the minor axis is at least about 2:1

[0023] Another aspect of the invention involves a ventricular patch torestore the ventricular architecture of the heart. The ventricular patchincludes a sheet of biocompatible material having a generally ovalconfiguration, and a continuous ring fixed to the sheet. The ring has agenerally oval configuration similar to the generally oval configurationof the sheet of biocompatible material. The ring defines a centralgenerally oval region of the patch inside the ring and a circumferentialregion of the patch outside of the ring. The central generally ovalregion has a major axis ranging from about 2 cm to about 8 cm and aminor axis ranging from about 0.5 cm to about 1 cm.

[0024] A further aspect of the invention involves a ventricular patch torestore the ventricular architecture of the heart. The ventricular patchincludes a sheet of biocompatible material having a generally ovalregion with a major axis and a minor axis. The ratio of the major axisto the minor axis is about 4:1. In a preferred implementation, thegenerally oval region has a major axis of about 4 cm and a minor axis ofabout 1 cm.

[0025] A still further aspect of the invention involves a ventricularpatch to restore the ventricular architecture of the heart. Theventricular patch includes a sheet of biocompatible material having agenerally oval region with a major axis and a minor axis. The ratio ofthe major axis to the minor axis is at least about 2:1.

[0026] A yet further aspect of the invention involves a ventricularpatch to restore the ventricular architecture of the heart. Theventricular patch includes a sheet of biocompatible material having agenerally oval region with a major axis ranging from about 2 cm to about8 cm and a minor axis ranging from about 0.5 cm to about 1 cm.

[0027] These and other features and advantages of the invention willbecome more apparent with a description of preferred embodiments andreference to the associated drawings.

DESCRIPTION OF THE DRAWINGS

[0028]FIG. 1 is a perspective view of the abdominal cavity of a humanbody showing the heart in cross section;

[0029]FIG. 2 is a front plan view of the heart showing coronary arterieswhich feed the septum, apex and lateral wall of the myocardium;

[0030]FIG. 3 is a axial cross section view of the ventricular portionsof the heart illustrating a dilated, generally spherical left ventricle;

[0031]FIG. 4 is an anterior elevation view of the heart with an incisioninto the left ventricle through dyskinetic scar tissue;

[0032]FIG. 5 is an anterior elevation view similar to FIG. 4 where theincision is made in marbled akinetic tissue;

[0033]FIG. 6 is an anterior elevation view similar to FIG. 5illustrating the incision made in normal-looking akinetic tissue;

[0034]FIG. 7 is a axial cross section view of the left ventricle showingthe surgeon's hand palpating the myocardium to define an imaginarycircumferential line of separation between viable and akinetic tissue;

[0035]FIG. 8 is a axial cross section view similar to FIG. 7illustrating the palpating heart and a preferred zone of placement for apatch associated with the present invention;

[0036]FIG. 9 is an anterior elevation view similar to FIG. 4 andillustrating placement of a Fontan stitch in the ventricular wall;

[0037]FIG. 10 is an axial cross section view illustrating a Fontan neckcreated by the Fontan stitch;

[0038]FIG. 11 is a side elevation view of the opening illustrated inFIG. 9 with the Fontan suture tightened to facilitate the natural ovalformation of the opening;

[0039]FIG. 12A is a plan view of sheet material included in oneembodiment of the patch associated with the present invention;

[0040]FIG. 12B is a cross section view taken along lines 12B-12B of FIG.12A and illustrating the sheet material in a concave configuration;

[0041]FIG. 13 is a top plan view of a ring associated with the patch ofthe present invention;

[0042]FIG. 14 is a circumferential cross section taken along lines 14-14of FIG. 13;

[0043]FIG. 15 is a top plan view showing the sheet material and ringcombined to form one embodiment of the patch of the present invention;

[0044]FIG. 16 is a cross section view of the patch taken along lines16-16 of FIG. 15;

[0045]FIG. 17 is a cross section view similar to FIG. 12B andillustrating the sheet material in a convex configuration;

[0046]FIG. 18 is a cross section view similar to FIG. 16 andillustrating the ring disposed on a concave surface of the sheetmaterial;

[0047]FIG. 19 is a cross section view similar to FIG. 18 andillustrating the ring sandwiched between two pieces of the sheetmaterial;

[0048]FIG. 20 is a cross section view similar to FIG. 19 andillustrating the ring sandwiched between two pieces of material, buthaving only a single layer in the center of the patch;

[0049]FIG. 21 is an anterior elevation view similar to FIG. 11 andillustrating the placement of pledgeted, interrupted sutures engagingthe patch in a remote location;

[0050]FIG. 22A is an axial cross section view of the left ventricleillustrating the patch being moved along the interrupted sutures fromthe remote location to the Fontan neck;

[0051]FIG. 22B is a perspective view similar to FIG. 21 and illustratingan alternative method for placement of interrupted sutures;

[0052]FIG. 23 is an axial cross section view similar to FIG. 22 andillustrating the patch in its final disposition against the Fontan neck,and further illustrating use of the hemostatic rim to control bleeding;

[0053]FIG. 24 is an axial cross section view of the ventricular portionof the heart, with the patch mounted in place, the ventricle wallrestored to its apical configuration, and the lateral ventricular wallclosed in overlapping relationship with the septum wall next to thepatch;

DESCRIPTION OF PREFERRED EMBODIMENTS AND BEST MODE OF THE INVENTION

[0054] Abdominal portions of the human body are illustrated in FIG. 1and designated by the reference numeral 10. The body 10 is merelyrepresentative of any mammalian body having a heart 12 which pumps bloodcontaining nutrients and oxygen, to vitalize tissue in all areas of thebody 10. Other organs of particular importance to this blood circulationprocess include the lungs 14 and 16, and the vasculature of the body 10including arteries which carry blood away from the heart 12 and veinswhich return blood to the heart 12.

[0055] The heart 12 typically includes four chambers, a right auricle18, a right ventricle 21, a left auricle 23 and a left ventricle 25. Ingeneral, the auricles 18 and 23 are receiving chambers and theventricles 21 and 25 are pumping chambers. Each of these chambers 18-25is associated with a respective function of the heart 12. For example,it is the purpose of the right auricle 18 to receive the deoxygenatedblood returning in the veins of the body 10, such as the femoral vein27. From the right auricle 18, the deoxygenated blood passes into theright ventricle 21 from which it is pumped through a pulmonary artery 30to the lungs 14 and 16.

[0056] Within the lungs 14 and 16, the deoxygenated blood isreoxygenated and returned to the left auricle 23 of the heart 12 througha pulmonary vein 32. From this chamber, the oxygenated blood passesthrough a mitral valve 34 into the left ventricle 25. With each beat ofthe heart 12, the left ventricle 25 contracts pumping the oxygenatedblood into the arteries of the body, such as the femoral artery 36.

[0057] The shape of the normal heart 12 is of particular interest as itdramatically affects the way that the blood is pumped. It will be noted,for example, that the left ventricle 25, which is the primary pumpingchamber, is somewhat elliptical, conical or apical in shape in that itis longer than it is wide and descends from a base 35 with a decreasingcross-sectional circumference, to a point or apex 37. The left ventricle25 is further defined by a lateral ventricle wall 38, and a septum 41which extends between the atrium 18, 23, and between the ventricles 21,25. The mitral valve 34 is situated in an antero-ventricular junction 42which extends laterally between the atrium 18, 23, and ventricles 21,25. The “base” of the inferior muscle is also in this general location.This wide base 35 extends to the apex 37 on the inferior cardiacsurface. In the area of the base 35, the muscle is relatively flat orslightly spherical compared to the curvilinear form in the anteriorwall. The muscle fiber orientation is maintained at approximately 60degrees from base 35 to apex 37 to maintain the torsional gradient whichfacilitates ejection. This orientation of fibers changes to accentuateejection, with less twisting at the base 35 and more twisting at theapex 37.

[0058] On the backside, the heart 12 has an inferior wall 44 that is notcurved or linear, but rather flat or slightly spherical inconfiguration. This inferior wall 44 extends from the antero-ventricularjunction 42, at the wide area of the heart, toward the apex 37.

[0059] The pumping of the blood from the left ventricle 25 isaccomplished by two types of motion. One of these motions is a simplesqueezing motion which occurs between the lateral wall 38 and the septum41 as illustrated by the arrows 43 and 45, respectively. The squeezingmotion occurs as a result of a thickening of the muscle fibers in themyocardium. This compresses the blood in the ventricle chamber 25 andejects it into the body 10. The thickening is reduced in diastole(before the heart is contracting) and increased in systole (when theheart is ejecting). This is seen easily by echocardiogram, and can beroutinely measured.

[0060] In addition to the squeezing, there is a twisting of fibers thatresults in thickening of the ventricular wall, and shortening of themuscle from the base 35 to the apex 37. This is the predominant aspectof left ventricle systole. The muscle untwists after twisting (when theheart is prepared to fill) during the first third of ventricularrelaxation.

[0061] The twisting or writhing motion which begins at the apex 37 andrises toward the base 35, as shown by the arrow 47. The rising writhingmotion occurs because the heart muscle fibers run in a circular orspiral direction around the heart 12. When these fibers constrict, theycause the heart to twist initially at the small area of the apex 37, butprogressively and ultimately to the wide area of the base 35.

[0062] Recent studies by MRI show that twisting in systole accounts forapproximately 80% of stroke volume, while untwisting (in diastole)accounts for 80% of left ventricle filling. This twisting and untwistingoccurs in the same muscle segments, as the ventricle shortens duringejection and lengthens after blood is ejected.

[0063] The amount of blood pumped from the left ventricle 25 divided bythe amount of blood available to be pumped is referred to as theejection fraction of the heart 12. Generally, the higher the ejectionfraction the more healthy the heart. A normal heart, for example, mayhave a total volume of one hundred milliliters and an ejection fractionof sixty percent. Under these circumstances, 60 milliliters of blood arepumped with each beat of the heart 12. It is this volume of blood in thenormal heart of this example, that is pumped with each beat to providenutrients including oxygen to the muscles and other tissues of the body10.

[0064] The muscles of the body, of course, include the heart muscle ormyocardium which defines the various chambers 18-25 of the heart 12.This heart muscle also requires the nutrients and oxygen of the blood inorder to remain viable. With reference to FIG. 2, it can be seen thatthe anterior or front side of the heart 12 receives oxygenated bloodthrough a common artery 58 which bifurcates into a septal artery branch52, which is directed toward the septum 41, and an anterior descendingartery 54 which is directed toward the apex 37 and the lateral ventriclewall 38.

[0065] The inferior wall 44 is supplied by the right coronary arterywhich also perfuses the septum 41. This wall 44 forms a triangle whichextends from the base 35 to the apex 37. Consequently, the apex 37 issupplied by both the anterior descending artery and the right coronaryartery.

[0066] When a blockage occurs in one of these coronary arteries, thatportion of the heart muscle which is fed by the blocked artery no longerreceives the oxygen needed to remain viable. These blockages typicallyoccur in the common artery 50 and in the septal artery branch 52. Whenthe common artery is involved, the septum 41, apex 37 and lateral wall38 all become ischemic or oxygen deprived. When only the septal arterybranch 52 is involved, the ischemic symptoms are limited primarily tothe septum 41 and the apex 37. In this latter case, the septum 41 isalmost always affected, the apex 31 is usually affected, and the lateralwall 38 is sometimes affected.

[0067] As the ischemia progresses through its various stages, theaffected myocardium dies losing its ability to contribute to the pumpingaction of the heart. The ischemic muscle is no longer capable ofcontracting so it cannot contribute to either squeezing or the twistingmotion required to pump blood. This non-contracting tissue is said to beakinetic. In severe cases the akinetic tissue, which is not capable ofcontracting, is in fact elastic so that blood pressure tends to developa bulge or expansion of the chamber. This is particularly detrimental asthe limited pumping action available, as the heart 12 loses even more ofits energy to pumping the bulge instead of the blood.

[0068] The body's reaction to ischemic infarction is of particularinterest. The body 10 seems to realize that with a reduced pumpingcapacity, the ejection fraction of the heart is automatically reduced.For example, the ejection fraction may drop from a normal sixty percentto perhaps twenty percent. Realizing that the body still requires thesame volume of blood for oxygen and nutrition, the body causes its heartto dilate or enlarge in size so that the smaller ejection fraction pumpsabout the same amount of blood. As noted, a normal heart with a bloodcapacity of seventy milliliters and an ejection fraction of sixtypercent would pump approximately 42 milliliters per beat. The body seemsto appreciate that this same volume per beat can be maintained by anejection fraction of only thirty-percent if the ventricle 25 enlarges toa capacity of 140 milliliters. This increase in volume, commonlyreferred to as “remodeling” not only changes the volume of the leftventricle 25, but also its shape. The heart 12 becomes greatly enlargedand the left ventricle 25 becomes more spherical in shape losing itsapex 37 as illustrated in FIG. 3. In this view, the stippled area ofcross section shows the ischemic or infracted region of the myocardium.

[0069] On the level of the muscle fibers, it has been noted thatdilation of the heart causes the fibers to reorient themselves so thatthey are directed away from the inner heart chamber containing theblood. As a consequence, the fibers are poorly oriented to accomplisheven the squeezing action as the lines of force become lessperpendicular to the heart wall. It will be noted that this change infiber orientation occurs as the heart dilates and moves from its normalelliptical shape to its dilated spherical shape. The spherical shapefurther reduces pumping efficiency since the fibers which normallyencircle the apex to facilitate writhing are changed to a more flattenedformation as a result of these spherical configurations. The resultingorientation of these fibers produce lines of force which are alsodirected laterally of the ventricle chamber 25. Thus, the dilatation andresulting spherical configuration greatly reduce contraction efficiency.It also raises myocardial oxygen demands as torsional defamation(strain) increases. When a remote muscle is supplied by a non-occludedvessel under stress, the remote muscle tends to contract inefficiently.

[0070] Although the remodeling of the heart 12 by the body 10 helps inmaintaining the blood flow, it places the heart wall under considerablestress which eventually can result in congestive heart failure. Whilemyocardial ischemia or infarction is the primary cause of death anddisability in this country, congestive heart failure is certainly thesecondary cause with over 400,000 cases reported annually. It is thispost-infarction congestive heart failure which is a primary focus of thepresent invention.

[0071] As noted, successful acute reprefusion by thrombolysis,percutaneous angioplasty, or urgent surgery can decrease early mortalityby reducing arrhythmia and cardiogenic shock. These procedures appliedin the early stages of ischemia can also aid in salvaging the epicardialsurface of the myocardium and thereby prevent akinetic tissue frombecoming dyskinetic. Notwithstanding these known methods ofintervention, cardiac dilation and subsequent congestive heart failureoccur in approximately fifty percent of the post-infarction patients.

[0072] Ventricular volume is not excessive or>100 ml/m² left ventricularend systolic volume. The akinetic lateral wall may containnon-functional (contractile tissue) that is hibernating. This indicatesviable tissue that improves contraction several months after completerevascularization or when ventricular volume is reduced to produce amore normal ventricular contour (i.e. ellipse). This recovery afterrevascularization can occur only when ventricular volume is not verylarge, or the left ventricular end systolic volume index>100 ml/m². Thisaspect of recovery of akinetic hibernating muscle is potentiallyimportant when the ventricular shape is changed surgically to go from asphere (failing heart) to a conical or apical (more normalconfiguration) contour.

[0073] The procedure of the present invention addresses the effects ofmyocardial infarction using a cardioprotective approach to restore thegeometry of the left ventricle. This is not a “remodeling” procedureautomatically produced by the body 10, nor a “reconstructive” procedurewhich leaves the heart with other than a normal geometry. Rather, thisis a procedure which attempts to “restore” the normal geometry, andparticularly the apical configuration of the left ventricle 25. Theprocedure reduces the volume of the left ventricle 25, but alsoincreases the percentage of the ventricle wall which is viable. Thisgreatly increases the ejection fraction of the heart and significantlyreduces heart stress.

[0074] With a primary purpose of reducing the left ventricle volume, theintent of the procedure initially is to remove that portion of the wallwhich is not capable of contracting. This, of course, includes thescarred dyskinetic segments, which are easy to visualize, but may alsoinclude akinetic segments, which do not contract despite their normalappearance.

[0075] An incision 61 is cut into the myocardial wall of the dilatedheart 12 as illustrated in FIG. 4. If the surrounding tissue isdyskinetic, it will typically be formed entirely of thin, elastic scartissue. It is the elasticity of this scar tissue which causes thedetrimental ballooning or bulging effects previous discussed.

[0076] In some cases, the tissue surrounding the incision 61 will besomewhat marbled as illustrated in FIG. 5 with patches of both scartissue 63 and viable red tissue 65. This marbled tissue is oftencharacterized by trabeculae 67 which form ridges along the inner surfaceor endothelium of the wall. In spite of the presence of some viabletissue 65, these marbled walls of the heart 12 may nevertheless beakinetic.

[0077] With reference to FIG. 6, it is apparent that the akineticportion of the myocardium may even appear to be viable with an absenceof white scar tissue and the presence of a full red color. Nevertheless,these portions are akinetic and offer no positive effect to the pumpingprocess.

[0078] Given these factors, it is apparent that a determination as towhere the akinetic portions begin and end cannot be a visualdetermination as relied on by the prior art. Although the visualappearance may be of some value in this determination, ultimately, onemust palpate the tissue as illustrated in FIG. 7. Note that thisemphasizes the importance of performing the restorative surgery on abeating heart. By palpating the myocardial wall, one can feel where thecontractions of the lateral ventricular wall 38 and the septum 41 beginand end. Without regard for color or other properties visuallydistinguishable, the palpating will usually indicate viable tissue onone side of an imaginary circumferential line 70, with akinetic anddyskinetic tissue on the other side of the imaginary line 70. Asdescribed in greater detail below, a patch 72 will ultimately bepositioned relative to this imaginary circumferential line 70 not onlyto reduce the volume of the left ventricle 25 but also to define thatreduced volume with a larger percentage of viable heart muscle.

[0079] After the preferred location of the patch 72 has been determinedrelative to the circumferential line 70, a continuous Fontan stitch 74can be placed in proximity to the line 70 as illustrated in FIG. 9. Thisstitch 74 produces an annular protrusion 76 which forms a neck 78relative to the imaginary line 70. This neck 78 initially may have around circular configuration as illustrated in FIG. 9. However, as thesuture 74 is tightened, the musculature of the myocardium will form anatural oval shape as illustrated in FIG. 11. It is this oval-shapedneck 78, formed by the Fontan stitch 74, which in its natural ovoidshape is particularly adapted to receive the patch 72 of the presentinvention.

[0080] Providing the patch 72 with a configuration complimentary to theovoid shape of the Fontan stitch 74 is believed to be of particularimportance and advantage to the present invention. In the past, patchesof a round, circular form were used. This form maintained the fibers intheir less efficient transverse orientation. This was especially true ofrigid and semi-rigid patches. As a result, the fiber contractioncontinued to be very inefficient. Providing the patch with an ovalconfiguration restores the apex 37 or elliptical form of the heart 12.On a muscle fiber level, the fibers are directed back to the moreefficient 60 degree orientation which produces lines of force moreperpendicular with respect to the heart wall 38. This reorientation ofthe lines of forces greatly increases contraction efficiency.

[0081] Of perhaps equal concern is the use of semi-rigid or rigid ringson the patches of the past. By keeping the edges of the patch in a rigidconfiguration, these rings have inhibited the natural tendency of theheart to form the remaining muscle into a normal apical chamber.

[0082] Construction of various embodiments of the patch 72 are discussedwith reference to FIGS. 12A-20. In the plan view of FIG. 12A, a sheetmaterial 81 is illustrated to have the shape of an ellipse with a majoraxis 83 between 30 and 50 millimeters and a minor axis 85 between 20 and30 millimeters. It is contemplated that the sheet material 81 can beprovided in two sizes, such as 20×30 millimeters and 30×40 millimeters.

[0083] The sheet material 81 may be formed, for example, from Dacron(Hemoshield), or polytetrafluroethylene (Gortex). However in a preferredembodiment, the sheet material 81 is formed of autologous pericardium,or some other fixed mammalium tissue such as bovine or porcinepericardium. Importantly, the sheet material 81 is preferably sized andconfigured with a shape similar to that of the Fontan neck 78 asillustrated in FIG. 11. As noted, this shape is non-circular andpreferably oval.

[0084] The sheet material 81 can have a generally flat planarconfiguration, or can be shaped as a section of a sphere. The sphericalshape can be achieved as illustrated in FIG. 12B by fixing thepericardium while it is stretched over a spherical die to form a concavesurface 91.

[0085] In addition to the sheet material 81, the patch 72 alsopreferably includes a ring 87 which will typically have a toroidalconfiguration with a circumferential cross section that is circular, asshown in FIG. 13. The ring will typically be formed of a plastic graftmaterial that can also be made of curled autogenous tissue such asfascia or pericardium. In general, the ring 87 can be formed from anybiocompatible material having a degree of flexibility suitable toprevent interference with the normal contractions of the heart 12.

[0086] The circumferential cross section view of FIG. 14 illustratesthat the ring 87 may be enclosed in a tubular sheath 90 which may beformed from woven Dacron, and incorporated to promote tissue ingrowth tothe patch 72.

[0087] The ring 87 will generally have a non-circular shape which may besimilar to but smaller than the shape of the material 81. Providing thering 87 with a shape similar to the material 81 will enable the ring 87to be attached to the material 81 as illustrated in FIGS. 15 and 16 witha body or internal oval 91 of the patch disposed within the ring 87, anda circumferential rim or flange 93 disposed outwardly of the ring 87.The rim 93 will preferably have a constant width around itscircumference. This width will typically be in a range between 5 and 10millimeters.

[0088] The internal oval 91 disposed within the ring 87 preferably has asubstantially oval configuration with a major axis 92 and a minor axis94. In an alternative preferred embodiment of the invention, the body orinternal oval 91 of the patch disposed within the ring 87 has a majoraxis of about 40 mm (4 cm) and a minor axis of about 10 mm (1 cm). Theratio of the major axis 92 to the minor axis 94 in this embodiment isabout 4:1 or 4. The inventors have determined that a more linear,longitudinally elongated internal oval or body 91 makes the ventricularshape, after patch placement, more elliptical, making resulting fiberorientation oblique and directed towards a conical apex 37. Although thepreferred major axis to minor axis ratio in this embodiment of the patchis about 4:1, ratios greater than 2:1 are also desirable for making theapex 37 more elliptical. The major axis 92 preferably may vary between20 mm (2 cm) and 80 mm (8 cm) and the minor axis preferably may varybetween 5 mm (0.5 cm) and 10 mm (1 cm).

[0089] Many variations on the patch 72 will be apparent from theforegoing discussion. For example, as illustrated in FIG. 17, the sheetmaterial 81 can be provided with a convex surface 95 facing the leftventricle 25 rather than the concave surface illustrated in FIG. 13. Asillustrated in FIGS. 16 and 18, the ring 87 can be disposed on eitherthe interior or exterior side of the material 81.

[0090] With reference to FIG. 18, the ring 87 can be attached to thematerial 81 by adhesive or by stitches 97 passing over the ring 87 andthrough the material 81. Alternatively, with reference to FIG. 19, thering 87 can be sandwiched between two pieces of the sheet material. Inthis case, a second piece of the sheet material 99 can be positioned onthe side of the ring 87 opposite to the sheet material 81. Appropriatesutures extending around the ring 87 and through the materials 81 and 99will sandwich the ring and maintain it in the preferred position. Withreference to FIG. 20, the second piece of material 99 can be formed as acircle with an inner diameter 100 less than that of the ring 87, and anouter diameter 102 generally equal to that of the material 81.

[0091] It will be appreciated that many variations on these preferredembodiments of the patch 82 will be apparent, each having a generallynon-circular sheet material, such as the material 81, and perhaps asomewhat flexible toroid or oval ring 87.

[0092] In a preferred method for placing the patch 72, interruptedsutures 105 can be threaded through the Fontan neck 78 as illustrated inFIG. 21. Where the tissue is soft, the sutures 105 can be looped throughpledgets 110 on the interior side of the neck 78 with the free ends ofthe sutures 105 extending through the exterior side of the neck 78.These free ends, emanating from progressive positions around thecircumferential neck 78, are passed in complementary positions throughthe body of the patch 72 which is initially positioned remotely of theneck 78 as illustrated in FIG. 21. Since the Fontan stitch 74 may beapplied to normal (although akinetic) tissue, the pledgets 110 arepreferred to insure that the sutures 105 are well anchored in the neck78.

[0093] Another method for placement of the interrupted patch suture isillustrated in FIGS. 22A and 22B. In this view, which is similar to FIG.21, interrupted sutures 111 are directed through the entire ventricularwall 38 and exit the wall 38 in proximity to the protrusion 76 whichforms the Fontan neck 78. These sutures 111 can also be anchored in apledged strip 113 disposed on the outer surface of the heart 12 tofurther enhance the anchoring of these sutures 111.

[0094] When all of the interrupted sutures 105 have been placed aroundthe circumference of the neck 87, the patch 72 can be moved from itsremote location along the sutures 105 and into proximity with the ovalneck 78. This step is illustrated in FIG. 22A where the patch 72 isembodied with the concave surface 90 facing the neck 78 and with thering 87 disposed outwardly of the material 81. After the patch 72 hasbeen moved into an abutting relationship with the neck 78, theinterrupted sutures 105 can be tied as illustrated in FIG. 23.

[0095] Having closed the left ventricular cavity 25 with the patch 72,one may proceed to address any bleeding which may have resulted fromplacement of the Fontan stitch 74 or the sutures 105, especially fromthe region of the septum 41. Such bleeding, illustrated by the referencenumeral 112 in FIG. 23, will typically occur in close proximity to theneck 78 and beneath the region covered by the rim or flange 93associated with the material 81 of the patch 72. This bleeding cannormally be stopped by merely placing a suture through the ventricularwall 38 and the rim 93 at the point of bleeding. A pledget 114 can beused to tie the suture 112 with the rim 93 closely held against thebleeding wall 38. This reinforcing stitch, acting in combination withthe rim 93 of the patch 72, will usually stop any bleeding associatedwith the sutures.

[0096] In the embodiment of the patch where the internal oval 91 is morelinear or longitudinally elongated (e.g., 10×40 mm internal oval), themethod of patch closure produces an oblique line. The lower margin is atthe apex, adjacent to the right or apical side of the anterior papillarymuscle. The closure extends from the lateral ventricle toward theseptum, that progressed along an intraventricular line to approximately2 cm below the aortic valve on the septum. The open width of the patchis ˜1 cm (within the oval) so that the suture which runs along the patchmargins can be used for hemostasis.

[0097] With the patch 72 suitably placed, the operative site can beclosed by joining the myocardial walls in a vest-over-pants relationshipas illustrated in FIG. 24. Care should be taken not to distort the rightventricle 21 by folding the septum wall 41 over the ventricular wall 38.Alternatively, the lateral wall 38 can be disposed interiorly of theseptum wall 41 so a majority of the force on the patch 72 is diverted tothe lateral wall 38. These walls 38 and 41 can be overlapped in closeproximity to the patch 72 in order to avoid creating any cavity betweenthe patch 72 and the walls 38, 41. When air evacuation is confirmed bytransesophageal echo, the patient can be weaned off bypass usually withminimal, if any, inotropic support. Decanulasation and closure isroutine.

[0098]FIG. 24 is positioned in proximity to FIG. 3 in order toillustrate the dramatic difference between the pre-operative dilatedheart of FIG. 3 and the post-operative apical heart of FIG. 24. Forcomparison it will again be noted that the dilated heart of FIG. 3 mighttypically have a left ventricular volume of 140 milliliters which mightproduce a blood flow of 42 milliliters with an ejection fraction of 30%.Comparing this with the postoperative heart of FIG. 24, it can be seeninitially that the ventricular volume is reduced for example to 90milliliters. The percentage of viable heart wall as opposed to akineticheart wall is greatly increased thereby providing an increase in theejection fraction, for example from thirty percent to forty-fivepercent. This combination results in a pumped blood volume of about 40milliliters with each beat of the heart 12.

[0099] These structural changes are somewhat quantitative inconsideration. But a further advantage, qualitative in nature, is alsoassociated with the present procedure. It will be noted that thisrestorative procedure provides the heart 12 with a more natural apicalconfiguration which facilitates the writhing action discussed withreference to the arrow 47 in FIG. 1. Thus, not only is the normal sizeof the heart achieved, but the restoration procedure also achieves anormal heart operation. In combination, the patch 72 and the resultingprocedure significantly reduce the long term effects of myocardialischemia and overcome many of the causes associated with congestiveheart failure.

[0100] It may be found that muscle function will be restored to someremote areas following the altered ventricular architecture. Althoughnot fully understood, it is believed that this restoration procedureimproves remote segmental myocardial contractility by reducing the walltension and stress in the myocardium due to a reduction in ventricularvolume. The stress equation states that —${Stress} = \frac{P \times R}{2h}$

[0101] where

[0102] P is blood pressure;

[0103] R is radius of the heart wall; and

[0104] h is wall thickness.

[0105] The late recovery of hibernating muscle, which may be present inakinetic muscle whose fiber orientation is directed helically (towardthe newly created apex). This progressive shape change may providefurther improvement in contractile function several months afterrestoration. Reducing the ventricular volume decreases the radius,increases the thickness, and thereby reduces wall stress. This improvesthe myocardial oxygen supply/demand relationship, but may also revivethe contractibility of otherwise normal but previously stressedmyocardium. At the very least, the reduced stress on the heart 12 isrelieved along with any potential for congestive heart failure.

[0106] A further advantages of this procedure relates to the incision 61in the left ventricle 25 which also provides access to the mitral valve34. Replacing this mitral valve 34 through the left ventricle 25 is muchsimpler than the present intra-atrial replacement procedure. Coronaryartery bypass grafts also can be more easily accommodatedintraoperatively. As a result, all of these repairs can be undertakenwith greater simplicity and reduced time. While blood cardioplegia maybe advantageously used for revascularization and valvular procedures, itwould appear that the restorative procedure is best accomplished withcontinuous profusion of the beating open heart for cardiac protection.

[0107] Placement of patch 70 can be further enhanced by providing in thepatch kit a plurality of sizing disks which can be individually held inproximity to the Fontan neck in order to determine appropriate patchsize. Similar discs, triangular in shape may be used for the inferiorrestoration process. The disks might have a generally planarconfiguration, and of course, would vary in size. Each disk might have acentrally located handle extending from the planar disk for ease of use.The patch 72 could be removably mounted on a holder also including adisk, on which the patch is mounted, and an elongate handle extendingfrom the disk to facilitate placement.

[0108] As further support for the restoration procedure, a specialsuture needle is contemplated which has a proximal end and a distal end.The proximal end is generally straight and accounts for more than halfof the length of the needle. The distal end is curved along a relativelylarge radius facilitating initial penetration of the thick heart wall.With this configuration, the needle can be easily introduced through thethick myocardium, but then pulled along a generally straight path as itis removed interiorly of the ventricle.

[0109] The goal of these procedures is to restore the heart 12 to itsnormal size, shape and function. This includes restoring the conicalapex of the heart in order to achieve the writhing pumping action. Thenonfunctioning segmental ventricular myocardium is excluded and replacedwith a patch so that the only akinetic wall of the ventricle is thatdefined by the small patch area. Not only is visual assessment enhanced,but more importantly, palpation affords the surgeon the ability tocarefully and accurately determine the circumferential line ofseparation between the contracting and noncontracting muscle. Thisdetermination is achieved although the muscle may have normal color andmay not contain either circular or trabecular scar tissue.

[0110] It is believed that cardioplegia arrest maybe deleterious toventricular function in the open ventricle because of nonuniform flowdistribution. By avoiding this cardioplegia arrest and operating on abeating heart, aortic cross clamping as well as the use of inter-aorticballoons and ventricular assist devices can be avoided. Patch placementcan be intraoperatively adjusted guided by echo or radio nucleotidedata. Placement of the patch is further simplified by creation of theFontan neck 78, and use of interrupted felt or pericardial pledgetedsutures 105. The circumferential rim 93 associated with the patch 72facilitates bleeding control without distortion of the patch 72.Finally, using a vest-over-pants closure of the excluded ventricleobliterates dead space and provides security against patch leaks andresultant expansion between the site of closure of the ejectingventricle with the patch, and where the excluded muscle is closed by theexcluded ventricle.

[0111] If the patch has a conical or elliptical contour, thepants-over-vest closure is excluded, so that progressive recovery ofpotentially hibernating muscle (previously akinetic) can occur so thatthe muscle itself forms the apex. The pants-over-vest closure mayprevent this, and that is the reason for excluding it.

[0112] Within these wide objectives and parameters, there will bevariations on the structure of the patch and the methods of restoration.Although the non-circular configuration of the sheet material and ringare believed to be critical, the shape of the patch 72 may vary widelyto provide the best anatomical fit with the natural shape of theventricle 25. The sheet material 81 may be composed of a variety ofmaterials, both natural and artificial. These materials may be woven ornonwoven to achieve a desired structure for the sheet material 81. Thering 87 may similarly be formed from a variety of materials and providedwith a variety of shapes in order to add structure to the patch 72without interfering with the normal contractions of the heart 12.Variations of the steps of the associated restoration method mightinclude mounting the patch with a convex surface facing the ventricularcavity, use of tissue adhesives are also contemplated for attachingsealing and otherwise fixing the patch 72 to the Fontan neck 78.

[0113] Given these wide variations, which are all within the scope ofthis concept, one is cautioned not to restrict the invention to theembodiments which have been specifically disclosed and illustrated, butrather encouraged to determine the scope of the invention only withreference to the following claims.

1. A ventricular patch to restore the ventricular architecture of theheart, comprising: a sheet of biocompatible material having a generallyoval configuration; a continuous ring fixed to the sheet and having agenerally oval configuration similar to the generally oval configurationof the sheet of biocompatible material, the ring defining a centralgenerally oval region of the patch inside the ring and a circumferentialregion of the patch outside of the ring, the central generally ovalregion having a major axis and a minor axis, the ratio of the major axisto the minor axis being about 4:1.
 2. The ventricular patch of claim 1,wherein the central generally oval region has a major axis of about 4 cmand a minor axis of about 1 cm.
 3. A ventricular patch to restore theventricular architecture of the heart, comprising: a sheet ofbiocompatible material having a generally oval configuration; acontinuous ring fixed to the sheet and having a generally ovalconfiguration similar to the generally oval configuration of the sheetof biocompatible material, the ring defining a central generally ovalregion of the patch inside the ring and a circumferential region of thepatch outside of the ring, the central generally oval region having amajor axis and a minor axis, the ratio of the major axis to the minoraxis being at least about 2:1.
 4. The ventricular patch of claim 3,wherein the central generally oval region has a major axis ranging fromabout 2 cm to about 8 cm and a minor axis ranging from about 0.5 cm toabout 1 cm.
 5. The ventricular patch of claim 3, wherein the ratio ofthe major axis to the minor axis is about 4:1.
 6. The ventricular patchof claim 3, wherein the central generally oval region has a major axisof about 4 cm and a minor axis of about 1 cm.
 7. A ventricular patch torestore the ventricular architecture of the heart, comprising: a sheetof biocompatible material having a generally oval configuration; acontinuous ring fixed to the sheet and having a generally ovalconfiguration similar to the generally oval configuration of the sheetof biocompatible material, the ring defining a central generally ovalregion of the patch inside the ring and a circumferential region of thepatch outside of the ring, the central generally oval region having amajor axis ranging from about 2 cm to about 8 cm and a minor axisranging from about 0.5 cm to about 1 cm.
 8. A ventricular patch torestore the ventricular architecture of the heart, comprising: a sheetof biocompatible material having a generally oval region with a majoraxis and a minor axis, the ratio of the major axis to the minor axisbeing about 4:1.
 9. The ventricular patch of claim 8, wherein thecentral generally oval region has a major axis of about 4 cm and a minoraxis of about 1 cm.
 10. A ventricular patch to restore the ventriculararchitecture of the heart, comprising: a sheet of biocompatible materialhaving a generally oval region with a major axis and a minor axis, theratio of the major axis to the minor axis being greater than about 2:1.11. The ventricular patch of claim 10, wherein the generally oval regionhas a major axis ranging from about 2 cm to about 8 cm and a minor axisranging from about 0.5 cm to about 1 cm.
 12. The ventricular patch ofclaim 10, wherein the ratio of the major axis to the minor axis is about4:1.
 13. The ventricular patch of claim 10, wherein the centralgenerally oval region has a major axis of about 4 cm and a minor axis ofabout 1 cm.
 14. A ventricular patch to restore the ventriculararchitecture of the heart, comprising: a sheet of biocompatible materialhaving a generally oval region with a major axis ranging from about 2 cmto about 8 cm and a minor axis ranging from about 0.5 cm to about 1 cm.